In recent years, particularly given the trend toward miniaturization in mobile phones, antennas of mobile phones are being designed to be retractable. One such antenna is disclosed in U.S. Pat. No. 5,710,567. Referring to this patent, the antenna device comprises a first extendable antenna and a second antenna. The first extendable antenna is movable between an extended position, where it switches on, and a retracted position, where it switches off. The first extendable antenna has a first holding device on its lower portion which cooperates with a second holding device arranged on a guide for the first extendable antenna. The holding devices cooperate to releasably lock the first extendable antenna in the extended position. The first and second holding devices comprise mutually and magnetically attractive elements. This locking means, however, requires use of magnetic elements, and thus the antenna assembly is complex, the production costs are relatively high, and the magnetic elements influence the received signals. Moreover, the first extendable antenna also requires another locking device for its retracted position. Furthermore, pulling out the first extendable antenna from the retracted position to the extended position requires two hands operating together, which is not convenient.
Therefore, an improved antenna structure for a mobile phone is desired which overcomes the disadvantages of the prior art.